This invention relates to shot pattern controlling devices for mounting or otherwise connected to a barrel of a shotgun. Particularly, the patent relates to devices for retarding the velocity of a wad/shot cup so as not to interfere with the shot or pellets emanating from the muzzle of the shotgun, producing a tighter or more compact pattern.
It is known to provide pins, discs, or spheres for protruding into a barrel of a shotgun to retard a fiber wad traveling down the barrel. U.S. Pat. No. 2,092,649 shows these features. It is also known to provide a semiannular rib in conjunction with a nozzle to cause wad retardation by imparting a spin to the wad as it progresses down the nozzle. U.S. Pat. No. 3,045,379 also discloses these features. It is also known to provide conventional chokes on a shotgun muzzle which offer a constriction or a constriction followed by an expansion to adjust the spray pattern. These restrictions can also slow down a wad traveling down the barrel but they apply radial forces to the shot pellets, thereby distorting the resulting pattern.
Because of pollution concerns, the use of lead shot may soon be restricted or outlawed. Lead is a soft metal which does not drastically wear the inside bore of a shotgun during firing. As an alternate to lead, other shot materials such as steel, zirconia, bismuth, etc., have the disadvantage of being sufficiently hard to wear or damage the inside surface of the barrel during discharge. Hence, in modern applications, shot is carried in a plastic shot cup formed as one piece with the wad separating the powder charge from the shot pellets to protect the inside surface of the barrel during discharge. However, it has been found that the shot cup, which is designed to split open near the muzzle end of the barrel or just outside the muzzle end of the barrel, left unretarded, can accelerate into the projecting shot or tip or twist before all of the shot pellets have left the shot cup, thus detrimentally affecting the shot pattern, e.g., making the pattern wider. Modern venturi or orifice chokes can act to retard the carrier cup, but additionally also affect the shot pattern.
Where a restriction such as a choke is used to retard the carrier cup, the choke adversely affects the shot pattern and in some cases makes the pattern too concentrated for effective shotgun hunting of game at a distance. Additionally, if the game is too close, an overly concentrated pattern will so destroy the game that it is not useable for food or otherwise.
It is not known to provide a protuberance-type wad retardation zone for use with modern plastic shot wad casings or shot carrier cups.
It is also not known in the art to provide a protuberance-type wad retardation zone followed by a choke or shot spreader in a downstream zone of the barrel.